Using the Pirani Gauge on the MRC

We have a pirani gauge that can be connected to the mrc to give more precise chamber pressure readings.

Using the Pirani Gauge on the MRC Etcher

What is the Pirani Gauge?

The Pirani gauge gives the user another more accurate way to
measure the chamber pressure of the tool.
The manometer readings are in mT and the Pirani reads in T. A typical Pirani reading is 5e-6 or 0.5mT.

Why would I want to use it?

Users may want to know with more precision what the base
pressure the system can attain. Users
may also want to do a rate-of-rise test on the system. And users who are doing O2 sensitive etches,
for example Ar sputter etching of metals, may want to make sure the system has
reached a low base pressure before starting to set up the etch.

How do I use it?

Go
through the normal pumpdown procedure to opening the gate valve.

Open
the gas inlet valve. This removes
the chance of a burst of gas going into the chamber.

Open
the Pirani gauge valve and monitor the chamber pressure by looking at the
black box on the wall behind the tool.

Monitor
the pressure for at least 8 minutes.

Close
the Pirani gauge valve before striking the plasma. The plasma may harm the Pirani sensor.

To
perform a rate-of-rise start a timer for one minute after closing the
Pirani gauge valve. The pressure
shown on the Pirani gauge readout at the end of the minute is the
rate-of-rise. Please note it in
coral. It should be less than
10mT/min.

Continue
with the standard operating instructions starting with ‘Toggle on selected
gases’ in the Section Pumping Down the Chamber.

Pirani gauge do’s and don’t’s;

Do not
have the gauge open while running the plasma. This will harm the sensor and eventually
render the gauge useless.

The
gauge may be exposed to atmosphere.
Unlike the manometer, the Pirani is fine in a vented condition on
the tool.